1. Field of the Invention
This invention relates to attenuating the vibrations in a shelf frame on which a plurality of tape drives or disk drives are mounted. More particularly, the invention relates to a composite member in a shelf frame on which the drives may be mounted and where the composite member is structured both for strength and for reducing vibrations in the shelf frame and thereby reduce vibrations in the drives.
2. Description of the Related Art
Racks or shelves for mounting multiple disk drives in an array have been designed for strength and low cost. Vibrations in the rack, or in a shelf of the rack, caused by the disk drive mechanisms has not been a significant problem, to date. As disk drives became smaller, operating first with 9-inch disks, then 51/4-inch disks and 31/2-inch and smaller disks, shock mounts for damping vibrations were eliminated from the disk drives because the drives were robust and were not susceptible to a vibration problem. However, as the recording density have increased and the revolutions per minute of the disks have increased, vibrations in the disk drives can give rise to vibrations in the shelves or in the mounting rack sufficient to cause read/write errors in the disk drives. For example, nine Gigabyte drives with 10,000 rpm disk speeds can create enough vibration that there is vibratory cross talk between drives mounted on the same shelf frame or cabinet. Especially with embedded servos alone being used in the disk drives to follow recorded tracks, vibrations in the mounting shelf frame may cause read/write errors in the disk drives.
Making the shelf frames stiffer is not a solution to the vibration problem. In fact, a stiffer shelf may vibrate at a resonant frequency corresponding to the desired disk speed for the disk drives. What is needed is a mounting shelf or shelf frame for the disk drives that has sufficient strength to support the drives and yet has damping properties to attenuate the vibrations in the shelf and shelf frame. This will decrease transmission of vibrations to the drives from sources external to shelf frame or shelf frame cabinet and from drives mounted on the shelf frame.